Brush apparatus



Dec. 12, 1967 B. WlLLlAMSON ET AL 3,357,038

BRUSH APPARATUS 2 Sheets-Sheet 1 Filed Aug. 19, 1966 INVENTORS' Ve/lo H.Ebrok /o W ATTORNEYJ Dec. 12, 1967 B, AMS N ET AL 3,357,038

BRUSH APPARATUS 2 Sheets-Sheet 2 Filed Aug. l9, 1966 INVENTORS BurrWI'I/Ibmson John L l/oel/mfcke, J1:

l/el/o H. Ebrok ATTORNEYS United States Patent ABSTRACT OF THEDISCLOSURE Rotary brushes having rotatable bases, strips having bristletuft receiving apertures and collars mounted on the bases, capped tuftplugs squeezed tightly within the apertures and collars, and bristleswelded within the plugs and the method of welding plugs and bristles aredescribed herein.

This invention concerns bristle tufts, brushes, and brush assemblies andmethods for their construction. The articles described herein areprimarily intended for use in rotary brushes, which are conventionallyused in pick-up brooms or street sweepers, and which are widely used forcleaning industrial areas, urban streets and airport runways and forremoving snow.

In rotary brushes for cleaning industrial floors, runways and streets,there have been developed many improvements, which facilitatemaintenance of sweeping equipment, which improve the quality ofoperations and results, and which increase brush life. One example ofrecent developments in this field is United States Patent No. 3,228,053,which was issued on Jan. 11, 1966. The quest goes on for better,stronger, easier to assemble, and more economical rotary sweepers; andthe present invention offers improvements in bristles, in grouping ofbristles, in brushes, and in brush assemblies, which meet demands forimproved products and for more economical methods of assembly.

The present brush employs oriented plastic bristles which are stretchedafter they are formed. The oriented bristles are tough and resilient,and the bristles maintain their alignment in tufts to create a desirableincreased snap or propulsive thrust as the grouped bristles are rotatedupward out of contact with a runway or street. The oriented plasticbristles have a good tensile strength and a desirable modulus ofelasticity; moreover, the bristles are neither prone nor subject tofatigue.

In order to achieve optimum sweeping performance, it is important thatthe plastic bristles have a stifl'ness characteristic sufficient toimpart a flipping action to debris on the surface being swept. Normally,when plastic bristles are dispersed uniformly around a broom, eachbristle acts individually and does not achieve its maximumeffectiveness. However, it has been found that when the bristles aregrouped in tufts and are tightly confined at the tuft base, each bristlemutually supports other bristles in the tuft and imparts a much superiorstiffness without dilatoriously effecting the fatigue resistance of thebristles. Actual tests have shown that plastic bristles so grouped andtufted will leave only about half the amount of debris on the road asthe same quantity of bristles uniformly distributed throughout thebroom. For instance, in one test, using identical pressure on thesurface being swept and identical broom speeds, the tufted plasticbristles left a residue of 11.95%, while the uniformly dispersed plasticbristles in a spirally wound strip left a residue of 20.80%. Tufted wirebristles mounted in exactly the same manner left 17.10% residue.

It is, therefore, desirable and important in order to obtain maximumresults from the bristles to group them and hold them tightly in aholding means. The central core structure, for instance, as shown in theaforementioned United States Patent No. 3,228,053, must be fabricated ofsteel or some other rigid material in order to transmit the properforces. At some point the plastic bristles must be fastened to thecentral core structure. Again, at this point, it is desirable andimportant that there be no relative motion between the plastic bristlesand the metallic structure, or both the plastic and the metal would besubject to excessive wear, which eventually would loosen the hold of themetal on the tuft of plastic bristles and, consequently, would decreasethe effective stiffness which is so desirable.

It has been found that if the plastic bristles are inserted in ametallic holding means in such a fashion that the metal is stretchedwithin its elastic limit as the bristle is inserted therein, or thebristles themselves are looped in a well-rounded bend and held so thatthe elastic limit of the bristle is not exceeded, then a retaining forceis developed by the properties of the material in such a fashion thatthe tuft is held firmly throughout the life of the broom. The co-actionbetween the metallic holding means and the plastic bristle is similarwhether the holding force is developed through a slight stretching ofthe metal or the bending of the plastic bristle.

In one embodiment of this principle, the plastic bristles are fused orconnected to plastic plugs or holding means, and these plugs are used tostretch metal collars which hold the plugs. In this case, it isbeneficial to construct bristles and holding means or plugs from similaror identical materials. Oriented plastics are extremely useful. Asuggested material for construction of the bristles and bristle holdersis polypropylene, although other alpha olefin homopolymers or copolymersmay be used less advantageously. Use may be made of other elastomericplastic bristles such as nylon, polyvinyl chloride, and polyurethanebristles, etc.

Since it is important that neither bristle segments nor bristles bethrown on streets, floors or runways, it is necessary that bristleholding means or joints between bristles and holding means be as strongas individual bristles. Airport sweepers particularly require strongjoints, since they rotate at 600 r.p.m. By using similar materials inthe holding means and bristles, joint strength is enhanced. Bristles arewelded in their holders by friction melting, through relatively spinningthe elements. The successive steps are aligning the bristles in tufts,forcing the ends of the bristles into the holders and spinning theholders or tufts to create frictional heat, thereby melting the interiorof the holders and ends of the bristles, flowing the two elementstogether and welding them.

Alternatively, the holders may be molded about the bristles, or thebristles and plug may be heated and fused. Bonding is another methodavailable for joining plugs and bristles. Since in a preferable formmaterials of the plugs and bristles are similar, the bonding materialwill have the same effect upon all elements of the joint.

The bristle holders or plugs may take any form, for example,cylindrical, rectangular or elliptical, providing that the mountingstrips are configured to receive the plugs. Although bristles usuallyextend perpendicularly from mounting strips, some bristles, notably endtufts may be disposed angularly from the strips. The latter form isparticularly useful with edge shoes, which conventionally are employedin rotary brushes.

As discussed in United States Patent No. 3,228,053, tufts of bristlesmay be mounted in metallic strips, and the strips may he slid intopermanent cores of rotary sweeping machines, so that worn brush sectionsmay be replaced. In order that the replaceable strips wear before thecore, the strips usually are made of aluminum. While 0 manufacturing thestrips, it is convenient and desirable to extrude perpendicular collarsabout holes which are punched in the strips to receive bristle tufts. Aspart of the subject matter of that patent, damper collars are addedbetween the aluminum collars and the bristles. These damper collarsfulfill their purpose by being resilient and by extending outward fromthe collars in order to curve wire bristles and to prevent their failureby fatigue from bending adjacent the collars.

It is extremely important in the present invention that bristles be heldtightly within the collars to prevent hammering and wearing away of thealuminum. If free play were permitted, impact of the bristles wouldenlarge the collars and would wear away the holders, which further wouldresult in increased momentums and impacts, which finally would destroythe apparatus or at least would destroy the effectiveness of the brush.In a preferable form of the present invention, plugs in which bristlesare mounted are relatively rigid. The plugs have an outside throatdiameter slightly larger than the inner diameter of the collars of themounting strips. The plugs are forced through the strips, and thealuminum collars are forced open within the limits of their elasticity.The aluminum collars, elastically seeking to contract, firmly hold theplugs in place. The hoop strength of the aluminum collars is so greatthat, once inserted, the plugs are held fast through the life of thebrush. Known elastomeric damper collars, which are made of rubber or ofneoprene, have been made identical in size or smaller than the metalcollars in which the damper collars fit. Consequently, the elastomericcollars do not enlarge the metallic collars within their elastic limits.Therefore, previously known damper collars do not take advantage of theelasticity and hoop strength of the collars.

Aluminum mounting strips have been tested and have been found to possessgood operational characteristics. Mounting strips may be made of othermaterials which are economical and which are readily deformable; carbonsteel and plastics are suitable.

As disclosed herein, mounting strips may be made of material similar tothe bristles, and mounting strips and plugs may be manufacturedintegrally. In the latter case, groups or tufts of bristles are insertedin the plugs, and the bristles are spun to create sufficient heat tocause mutual flowing of the plugs and bristles, which produces weldedjoints. Variations in strength, resiliency and hardness of the materialsmay be controlled conventionally by adding pigments to the rawmaterials. Made in but a single form, plastic strips may be mountedlongitudinally in keyways as shown in FIGURE 6, or the strips may becircularly bent as shown in FIGURE to fit rotary brushes made up ofadjacent circular elements. The latter form has an advantage ofproviding universal refills for brushes of uniform diameter and ofvarying lengths.

One objective of this invention is the providing of improved tufts ofbristles for street sweeping machines.

This invention has as another important purpose, the providing ofimproved bristle mountings for brushes.

This invention has as another objective, the provision of novel brushassemblies.

Another important purpose of this invention is the provision of novelmounting strips and tuft assemblies.

This invention has as a further objective, the provision of methods forjoining bristles and holders.

Further objectives of this invention will be apparent from thespecification and from the drawings in which:

FIGURE 1 is a perspective view of a rotary street sweeper of a typedescribed herein;

FIGURE 2 is a perspective view of bristles assembled in a plug;

FIGURE 3 is a perspective view of a mounting strip in which a tuft ofbristles has been mounted, and from which a section has been removed toreveal details of the punched holes and extruded collars;

FIGURE 4 is a perspective view of a mounting strip having integrallyformed bristle holding means;

FIGURE 5 is a side elevation detailing one form of suggested use for theintegrally formed mounting strip shown in FIGURE 4;

FIGURE 6 is an end elevation of a mounting strip core mounting devicewhich may be bolted or otherwise fixed on the core or drum of acylindrical brush;

FIGURE 7 is a schematic detail of steps in an assembly process forsecuring bristles in holding means or plugs;

FIGURE 8 is an alternate form of the assembly process.

Referring to the drawings, FIGURE 1 reveals one type of runway andstreet cleaning rotary brushes discussed herein. Pickup brush 1 sweepsdirt into hopper 2; the process conventionally employs conveyors to liftdirt and sweepings into the hopper. Extremely beneficial to the sweepingprocess is the flicking or snapping of the ends of bristles as theyleave the ground. The preferred oriented polypropylene bristlesdisclosed herein have suflicient resiliency and strength and tendency toremain in tufts to provide good flicking or snapping characteristics.

A bristle mounting means of plug 30, as illustrated in FIGURE 2, has athroat 32 and a cap 34. A circular opening at the base of throat 32reveals a hollow cylindrical wall which receives a tuft of bristles 10.Ends 12 of bristles 10 are forced into cylindrical opening 32 in plug30, and the bristles are clamped while plug 30 is spun, creatingfrictional heat, melting and fusing the materials, and welding bristles10 to plug 30, as shown in FIGURE 7. Alternatively, the plugs may beclamped, and the tufts may be spun.

In FIGURE 3, aluminum tuft mounting strip 40 is cut away to illustratethe formation of tuft mounting holes and collars which are made with aninternal diameter equal to or slightly less than the outer diameter ofplug throat 32, to ensure a tight fit. Differences in the diameters areheld within the elastic limit of aluminum so that when collar 44 isstretched upon the insertion of throat 32, the aluminum annulus isexpanded elastically. The hoop strength of collar 44 is brought to bearin its contraction, effecting a tight hold on throat 32. The throat mustbe larger than the collar, or at least must be the same size to preventhammering of bristles 10 and plug 30 against the aluminum collar 44.

FIGURE 4 illustrates another embodiment of the invention in whichbristle holders or plugs 50 and mounting strip 60 are constructed as anintegral piece. Friction welding of bristles 10 in plugs 50 may beaccomplished by clamping mounting strip 60, forcing tufts of bristles 10into plugs 50, and spinning the tufts to create heat and fuse thematerials, as shown in FIGURE 7. Polypropylene strips 60 may be attachedto rotary brush cores of varying length by bending strips 60 intocircular sections 70 as shown in FIGURE 5. If variations in hardness andresiliency are desired between the strips, plugs, and bristles, plasticcompositions may be varied.

Strips 40 having tufts of bristles 10 mounted therein may be held on thecore of a cylindrical brush assembly 1 by a plurality of mountingchannels 80, as illustrated in FIGURE 6. Central ridges 82 of channelsare fastened to the brush core with fasteners 90. Lobes 84 of channel 80hold strip 40 firmly in place. Although this invention has beendescribed with specif- 1c embodiments, many modifications and variationswill be obvious to those skilled in the art. The invention is notlimited to the disclosed examples; rather, the limits of the inventionare precisely defined only in the following claims.

What is claimed is:

1. Rotary brush apparatus comprising a brush base mounted for rotationon a vehicle; a plurality of bristletuft elongated mounting stripshaving first and second opposite sides mounted on said base with thesecond sides facing the base, said strips defining a plurality ofapertures aligned longitudinally in said strips, said strips furthercomprising right oriented collars integrally extending from first sidesof the strips and surrounding the apertures; a plurality of bristleholders mounted in the strips, said bristle holders defining integralthroat and cap portions, said throat portions defining central bristlereceiving recesses and being forcefully positioned within the aperturesand collars of the mounting strips, external dimensions of the throatportions being slightly greater than corresponding internal dimensionsof the apertures and collars of the mounting strips, whereby residualopposing stresses remain in said throat portions and in said aperturesand collars, said cap portions overlying areas of said second sides ofsaid strips adjacent the apertures, and a plurality of bristles anchoredwithin said holders.

2. Rotary brush apparatus of claim 1 wherein said bristles comprisehairpin bristles having bends tightly wedged within the holders.

3. Rotary brush apparatus of claim 1 wherein said bristles are tightlywelded within the holders.

4. Rotary brush apparatus of claim 1 wherein the elongated mountingstrips and integral collars are aluminum.

5. Rotary brush apparatus comprising a brush base mounted for rotationon a vehicle, a plurality of bristletuft elongated mounting stripshaving first and second opposite sides mounted on said base with thesecond sides facing the base, said strips defining apertures alignedlongitudinally in said strips, said strips further comprising rightoriented collars extending from the first sides of the strips andsurrounding the apertures and a plurality of bristle tufts welded in thecollars and apertures.

6. Rotary brush apparatus comprising a brush base mounted for rotationon a vehicle; a plurality of bristle tuft elongated aluminum mountingstrips having first and second opposite fiat sides mounted on said basewith said second side facing said base, said strips defining a pluralityof stamped apertures aligned longitudinally in said strips, said stripsfurther comprising a plurality of integral extruded right orientedcollars surrounding the apertures on the first side of said strips; aplurality of thermoplastic bristle holders mounted in the strips, saidholders comprising integral cap and throat portions, said throat portiondefining bristle receiving recesses extending from walls of said throatportions opposite said cap portions to said cap portions, said throatportions being forcefully positioned within the apertures and collars ofsaid strips, external dimensions of the throat portions being slightlygreater than corresponding internal diameters of the apertures andcollars, and the cap portions overlying areas of the second sides of thestrips adjacent the apertures, whereby opposing stresses remain in theholders and in the apertures and collars; and a plurality of likethermoplastic bristles disposed in the recesses of the holders andWelded to the holders, thermoplastic material of the holders andbristles being interspersed.

7. Rotary brush apparatus comprising elements which are a cylindricalbristle holder having a cap and throat, and a tuft of bristles insertedin the throat, wherein said elements comprise like materials, andwherein each of said elements is fused into the other.

References Cited UNITED STATES PATENTS 347,048 8/1886 Kane 15-191846,003 3/1907 Brantley 15-190 X 2,672,640 3/1954 Peterson 61; a1 151602,878,069 3/1959 Wessel 15-192 X 3,029,456 4/ 1962 Pharo 15-4803,216,038 11/1965 Gould et al. 15--159.1 3,228,053 1/1966 Horton et a115-183 FOREIGN PATENTS 348,750 5/1937 Italy.

CHARLES A. WILLMUTH, Primary Examiner. P. FELDMAN, Assistant Examiner.

7. ROTARY BRUSH APPARATUS COMPRISING ELEMENTS WHICH ARE A CYLINDRICALBRISTLE HOLDER HAVING A CAP AND THROAT, AND A TUFT OF BRISTLES INSERTEDIN THE THROAT, WHEREIN SAID ELEMENTS COMPRISE LIKE MATERIALS, ANDWHEREIN EACH OF SAID ELEMENTS IS FUSED INTO THE OTHER.